Dimethyl-(methylphenyl)-phosphates



2,911,431 Patented Nov. 3, 1959 ice 2,911,431 DINETHYL-(METHYLPI-IENYL)-PHOSPHATES Harold D. Orlofi, Oak Park, Mich., and Francis X.

Markley, Bound Brook, N.J., assiguors to Ethyl Corporation, New York, N.Y., a corporation of Delaware No Drawing. Application February 28, 1958 Serial No. 718,135

4 Claims. Cl. 260-461) This invention relates to dimethyl-(monopheny1)- phosphates.

Organic compounds of phosphorus have been suggested as gasoline additives to reduce autoignition, spark plug fouling, and associated problems. However, for

one or more reasons, phosphorus compounds known and so used heretofore have not been entirely satisfactory. Typical limitations hindering otherwise acceptable additives include instability, low hydrocarbon solubility, high water solubility, corrosiveness, insuflicient engine inductibility, and characteristics promoting reduction in antiknock effectiveness and loss of exhaust valve life.

An object of this invention is to provide new and useful phosphates. Another object is to provide phosphorus compounds which by virtue of their properties are Well suited for use as addition agents to hydrocarbons of the gasoline boiling range and for other purposes. A further object is to provide both improved fuel compositions for spark ignition internal combustion engines and composite additives for gasoline.

It has now been found that the above and other objects of this invention are provided by dimethyl-(monophenyi)-phosphates having the formula wherein R, R and R" are methyl radicals and x, y, and z can be the same or different integers and are from to 1 so that the total number of carbon atoms of R, R and R" is from 1 to 3. Putting it another way, R is methyl, while R and R" are hydrogen or methyl.

The properties of our novel phosphates make them particularly useful as gasoline additives. Thus, we provide improved fuels for spark ignition engines comprising a hydrocarbon of the gasoline boiling range and a dimethyl-(monophenyl)-phosphate as described above. Such fuels preferably contain an organolead antiknock agent. Also provided by the characteristics of our compounds are improved composite additives for fuel for spark ignition engines comprising an organolead antiknock agent and one or more of our novel phosphates.

The esters of this invention can be prepared by reacting dimethyl phosphoryl chloride with the appropriate sodium phenoxide formed in aqueous solution. The reaction is carried out by contacting approximately equimolar proportions of these reagents while maintaining the temperature at about 25 C. A moderate excess of the particular sodium phenoxide may be used, the ex- .cess being about 0.5. of a mole over theoretical.

The above process is carried out with agitation, and

since the reaction is somewhat exothermic, temperature control is maintained by regulation of the rate of addition of the reactants as well as by conducting the reaction in such a manner that heat can be removed therefrom.

Upon completion of the reaction, the reaction mixture is extracted with a suitable organic solvent, such as carbon tetrachloride, followed by water washing. The re-' sulting product is then dried and distilled at reduced pressure.

Dimethyl phosphoryl chloride used as a starting material is conveniently prepared by reacting dimethyl hydrogen phosphite with chlorine gas, the reactants being in approximately equimolar proportions. The temperature of this reaction is kept below about 20 C. by controlling the rate of addition of the chlorine gas. Hydrogen chloride gas liberated in this reaction is removed by any convenient means, such as aspiration or air blowing.

The following examples, wherein all parts and percentages are by weight, illustrate the preparation of the novelesters of this invention.

EXAMPLE I parts of dimethyl hydrogen phosphite was reacted with incremental portions of clorine gas while maintainin the temperature below 15 C. Hydrogen chloride formed was stripped off While stirring the reaction mixture maintained at a pressure of 20 millimeters of mercury. The product of this reaction was added to 152 parts of m-cresol dissolved in approximately 160 parts of a 40 percent aqueous sodium hydroxide solution. This addition occurred over a period of 30 minutes while maintaining the temperature ,at 25 C. 200 parts of water was then added to the reaction mixture which was then extracted with carbon tetrachloride. The crude product was washed, dried, and purified by distillation at one millimeter of mercury pressure. 113 parts of purified dimethyl m-tolyl phosphate having a boiling range of 113-115 f C. at one millimeter of mercury pressure was formed. Analysis revealed 14.5 percent of phosphorus corresponding to the formula C H O P. Dimethyl m-tolyl phosphate has a boiling point of 171.0 Cat 20 millimeters of mercury pressure and has a refractive index of n 1.4910.

EXAMPLE II Using the procedure of Example I, 160 parts of the sodium salt of 2,4,6-trimethyl phenol is reacted with parts of dimethyl phosphoryl chloride. Dimethyl-(2,4,6- trimethylphenyl) phosphate is formed.

EXAMPLE HI 144 parts of the sodium salt of 2,3-dimethyl phenol (vicinal-o-xylenol) is reacted with 145 parts of dimethyl phosphoryl chloride at a temperature of 20 C. The resulting product is dimethyl (2,3-dimethylpheny1)-phosphate.

EXAMPLE IV Dimethyl p-tolyl phosphate is prepared by reacting 73 parts of dimethyl phosphoryl chloride with 65 parts of the sodium salt-of p-cresol at a temperature of 25 C. Dimethyl p-tolyl phosphate was found to contain 14.2 percent of phosphorus, to have a boiling point of 172.2 C. at 20 millimeters of mercury pressure, and to have a refractive index of 11 1.4896.

3 EXAMPLE v 73 parts of dimethyl phosphoryl chloride is added-portion-wise to 80 parts of the sodium salt of 3,5-dimethy1 phenol. The temperature is held at 25 C. Formed is dimethyl (3,5 dimethylphenyl)-phosphate which contains 13.5 percent of phosphorus, boils at 177.0 C. at 20 millimeters of mercury pressure, and has a refractive index of n 1.4946. A

7 EXA ,Dimethyl o-tolyl phosphate is prepared by reacting at 30. C. 82.5 parts of dimethyl phosphoryl chlorideand 146 partsof the sodium. salt of o-cresol.

EXAMPLE VII 110 parts of dimethyl phosphoryl chloride is added portion-wise to a 30 percent aqueous solution of the sodium salt of 2.4.5-trimethyl phenol. The mixture is stirred while holding the temperature at 25, C. Di-

methyl-(2,4,5-trimethylphenyl)-phosphate is formed.

EXAMPLE VIII 130 parts of the sodium salt of mixed meta-para cresol (the cresols boiling at 200203 C. and containing 60 percent of the meta isomer) is reacted at 25 C. with 145 parts of dimethyl phosphoryl chloride. The product is dimethyl tolyl phosphate (mixed isomers).

EXAMPLE IX EXAMPLE X The procedure of Example I is repeated with the exception that 130 parts of the sodium salt of USP cresol containing ortho-, metaand para-cresols (boiling range of the cresol, 195-205 C.) is used as a starting material. The resulting product is dimethyl tolyl phosphate (mixed'isomers).

By suitable choice of starting materials the various compounds of this invention'can be obtained in high yield and purity. Thus, we can prepare dimethyl monophenyl phosphates where the phenyl group is substituted 'with from 1 to 3 methyl groups from such phenolic compounds as 0rth0-, meta-, oripara-cresol; xylenols, s'uch as 2,3-dimethyl phenol, 3,4-dimethyl phenol, 3,5- 'dimethyl phenol, 2,6-dimethy1 phenol, 2,4-dimethyl phenol and 2,5-dimethyl phenol; and'trimethyl phenols, such as 2,3,4-trimethyl phenol, 2,3,5-trimethyl phenol, 2,3,6-trimethyl phenol, 2,4,5-trimethyl phenol, 2,4,6-trimethyl phenol, etc. Mixtures of appropriate phenolic compounds may also be usedin preparing our compounds, a mixture obtainedby-coal-hydrogenation. and containing predominantly Xylenols and cresols being particularly preferred because of its low cost and ready availability.

Thenovel esters of this invention'are colorless liquids which are highly soluble in most organic solvents. For

example, our esters are soluble in all proportions at 25 C. in various gasoline stocks, such as straight runfuels; cracked fuels-resulting from thermal and catalytic processes; and other fuel types, .such as obtained by reforming, catalytic reforming or alkylation.

The phosphates of this invention when present zin leaded gasoline in which the lead content is as 'much as 6.3 grams per gallon reduce deposit-induced autoignition, also .known as wild' ping. In this capacity, :our esters act as ignition control compounds by" suppressing the erratic uncontrolled ignition occurring at a period in U1? P9 1 bustion cycle diiferent' from that produced by the spark. The use of such fuels also results in the alleviation of spark plug fouling, our compounds being exceedingly eiiective in this regard.

As an additive to leaded hydrocarbons of the gasoline boiling range, we employ our compounds in amount from about 0.05 to 0.5 theory of phosphorus, a theory of phosphorus being defined as the amount of phosphorus theoretically required to react with the lead to form lead ortho. phosphate, namely, two atoms of phosphorus per every three atoms of lead. This amount is suflicientto reduce deposit-induced autoignition.

The following examples wherein parts are by weight illustrate the manner in' which improved fuel compositions of the present invention are prepared.

7 EXAMPLE XI EXAMPLE XII To 3000 parts of a high octane quality aviation fuel base stock containing 7.59 parts of tetraethyllead as an antiknockfluid comprising tetraethyllead and 1.0 theory of bromine as ethylene dibromide is added 1.08 parts of dimethyl-(3,5-dimethylphenyl)-phosphate. Agitation of this mixture produces a homogeneous improved fuel composition of this invention containing about 0.3 theory of phosphorus as dimethyl-(3,5 dimethylphenyl)-phosphate.

Example XI is illustrative of the'manner in which a typical automotive fuel of this invention is compounded. The preparation of a typical aviation fuel of our invention is described in Example XII. 'Suchfuels reduce wild ping rate by as much as 80 percent of that produced by the same fuels in the absence of our compound.

Besides having inherent'efr'ectiveness as 'an ignition control compound, the novel esters of this invention have a number of characteristics further enhancing their utility in this regard. They exhibit substantially no adverse effect on tetraethyllead antiknock' effectiveness. They are readily blended with gasoline hydrocarbons, are compatible on storage in gasolines containing lead alkyl antiknock agents, and are highly inductible in multi-cylinder engines. Moreover,-;our esters are only sparingly soluble in water and resist hydrolysis. Furthermore, our esters provide all of the foregoing 'unique' technical advantages atvery low cost because of the cheapness and availability ofthe raw'materials which go into their manufacture.

An outstanding characteristic of our esters is that they exhibit substantially no adverse effect on tetraethyllead antiknock effectiveness; To illustrate, individual portions of a representative gasoline containing 3.0 milliliters .oftet'raethyllead per gallon as an antiknockfluid comprising tetraethyllead, 0.5 theory of bromine as ethylene dibromide, and 1.0 theory of chlorine as ethylene dichlorid'e -each portion containing a given concentration of phosphorus as dimethyl m -toly1 phosphatewere subjected to the standard 'ASTM Research Method, Test Procedure D 908 (which can be found in the 1952 edition of ASTM Manual' of Engine Test Methodsfor Rating'Fuels). As comparisons, individual portions of the same fuel containing the same amount of the antiknock fluid above describedand identicaLconcentrations of. phosphorusia'svarious additives suggested heretofore were subjected to'thesanle test procedure. The results of these tests are'shown in Table I. 1 1

- l 6 invention is shown in Table'II' are percent by weight.

wherein the figures given Concentration of Phos- Table II phorus Additive 5 Component Aviation Automotive 0.2 T 0.5 T Fluids Fluids Dimethyl m-totyl phosphate 0 Tetraethyllead 54.02 to 60.58 54.07 to 60.65 Trimethyl phosphate. 2 Ethylene dibromide. 31.38 to 35.19 15.71 to 17.62 Tricresyl phosphate 2.5 3 Ethylene dichloride 16,54 to 18.56 Tri-n-butyl phosphite. 1 5 Dye, kerosene, impurities 2.57 to 2.88 1.03 to- 1.83 Dlmethyl mtolyl phosphate 1.35 to 12.03 1.35 to 12.05

The phosphates of this invention being hydrocarbon When blended with non-leaded hydrocarbons of the soluble liquids can be blended directly into the refinery gasoline boiling range, our esters beneficially modify the stream by means of liquid proportioning pumps or the nature and properties of deposits which have previously like, or gasoline concentrates, such as 10 percent soluaccumulated in the engine. Consequently, the presence tions, can be readily prepared and similarly used. of one or more of the novel'pho'sphate esters of this in- When stored at a temperature of 110 F. for long vention in amount up to about 65 pounds per 1000 barperiods of time, leaded gasoline containing 0.2 T of rels of gasoline results in the alleviation of depositphosphorus as the phosphates of this invention show virinduced autoignition and spark plug fouling. tually no signs of decomposition or sludge formation. In the fuel and antiknock fluid embodiments of this Our compounds are highly inductible in multi-cylinder invention, we can use our esters with various organic engines. During manifolding Where more or less evapohalide scavengers, such as trichlorobenzene, dibromotoluration of the fuel occurs, our esters are soluble in the ones, and, in general, those disclosed in US. Patents heavy ends to such an extent that they remain in solution 1,592,954; 1,668,022; 2,364,921; 2,479,900; 2,479,901; even after most of the more volatile fuel components have 2,479,902; 2,479,903 and 2,496,983. When we use mixvaporized. Thus, our compounds present no induction tures of chloroand bromohydrocarbons as scavengers system deposit problems. Our esters also ave been we prefer concentrations and proportions as described in found by engine tests to be powerful anti-icers or anti- US. Patent 2,398,281. stalling agents- The organolead antiknock agents used in the antiknock The n v l esters of this invention are pfflhtically fuel and fluid embodiments of our invention are hydro insoluble in water, having a solubility at 25 C. or less carbon lead compounds, that is, lead alkyls, such as than 1 p This further ehahlfis 0hr COmPOUIIdS t0 ramethyllead, tetraethyllead, tetrapropyllead, dimethyl dibe used as fuel additives since they remain dissolved in h ll d, i h l h ll d, d l d aryls, h as tetrathe fuel even when stored over water. Furthermore, our h n d, H 1 i i Compounds, h as icompounds are hydrolytically stable and are thus not th flead b id may l o b u ed, Subject to deteriolatiilh resulting from the Presence of The novel esters of this invention are useful as addi- Water which is invariably Present in Commercial gasotives to lubricating oils particularly those having a vislinecosity from about 30 seconds at 100 F. to about 250 Still another feature of the esters of this invention is Seconds at 210 B wh so l d, our compounds their 1111115113113 low molecular Weight as compared with serve to reduce oxidation of the oil and its tendency to thfi Vast j y of Prior art gasoline additives- This thicken at low temperatures while reducing bearing cormeans that the p 'hhds of this invention contain a rosion and improving lubricating characteristics, particu- Y high Percentage of Phosphorus in the molecule and larly of those oils designed for extreme pressure service, this is a distinct technical and economic advantage. It is h as h id gear l b i t c t ti f our thus very surprising that the compounds of this invention esters up to b t 5 ercent by weight or higher can be are so ins lu l in Water and Y miscible in all P P used. However, ordinarily it is sufiicient if the concentions with gasolines because as a general rule, low molec- {ration is l h about one percent b i ht, Hiar Weight Prior aft Phosphorus compgunds are quite Our esters are also useful as fireproofing agents, parsolu lc in Water and have low gasoline sohlhiiity- Here ticularly of normally inflammable textile materials. Not tofore t a t has found it necessary to resort high only do the phosphates of this invention render such mamfllechlal' Weight P P Compounds Where the P terials as yarns and plastic compositions (e.g., cellulose P110111S Commit is low in Order to achieve satisfactflry acetate) fireproof without affecting their softness and gasoline Solubility and sufifllciehtiy low water Solubilitydraping qualities, but because our esters do not possess Consequently, this invention makes available for the first the property f irritating h n skin such utility is onim c mp Which 3Y6 rich in Phosphorus: miscible hanced. Our esters are also useful as plasticizers parin gasolines, essentially insoluble in water, stable to hyticularly f vinyl resilm F example, our esters are drolysis and very highly inductible into gasoline englnes capable of lowering the brittle point and iff f poly- Wher they exert tramfihdolls eitectivehess in Overcoming vinyl chloride when employed therein in relatively small wild ping and spark plug fouling without interfering with concentrations, the antiknock eifectiveness of the organo lead antiknock This application is a continuationqmpart f our prior agent with Which y are ptefelahiy empioyedco-pending application, Serial No. 445,898, filed July Another embodiment of this invention relates to 1m- 26, 954 proved antiknock fluids, i.e., composite additives. Com- AS many Widely djfl j variations f h Present mercial practice involves the provision of anttknock invention are ibl i h t departing f th spirit fluids wh CC'IYIPIFiSe OIgaIlO-iead antiknock agents, and scope thereof, it is not intended that this invention be tably tetraethyllead, one or more halogen scavengers and limited except as defined by the d d i a blending agent, such as kerosene. Such fluids also con- We claim: will Organic dyes and may contain antioxidants, rust 1. Dimethyl-(monophenyl)-phosphates having the forhibitors, anti-icing agents, and the like. Thus, to further mula facilitate blending procedures, we provide antiknock 0 fluids containing from about 0.05 to about 0.5 theory of phosphorus as one or more of the novel phosphate R t rs of this invention. 1 es 'l he composition of typical antiknock fluids of this wherein R, R and R" are methyl radicals and x, y and z a re integers from O to 1, least one of x, y and z being 'ohe' so'that the total number of cax bonatoms f'R, R

and R" is from 1 to 3.

2. 'Dimethyl m-tolyl phosphate. 3. Dimethyl tolyl phosphate. 5 4. Dimethyl xylylphosphate. 7

References ited in the file of this patent v UNITED STATE S'PATENTS' 2,250,662. Walter July 29, 1941 

1. DIMETHYL-(MONOPHENYL)-PHOSPHATES HAVING THE FORMULA 